JP2013133453A - Fuel-efficient lubricating oil composition for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition for internal combustion engines with high fuel saving effect.SOLUTION: The lubricating oil composition for internal combustion engines contains a lubricating base oil and a lubricating oil additive including an overbased metal-containing detergent and a molybdenum-containing friction modifier, in which the overbased metal-containing detergent includes calcium salicylate having an alkyl group having an average carbon atom number of 14-18, at least 60 mol% of the alkyl group having a carbon atom number of 14-18, and calcium sulfonate having an alkyl group having an average carbon atom number of 20-24, at least 60 mol% of the alkyl group having a carbon atom number of 20-24, and/or calcium salicylate having an alkyl group having an average carbon atom number of 20-28, at least 60 mol% of the alkyl group having a carbon atom number of 20-28.

Description

  The present invention relates to a lubricating oil composition useful for lubricating an internal combustion engine used on land such as a gasoline engine, a diesel engine, or a gas engine that exhibits high fuel efficiency when used as a lubricating oil composition for an internal combustion engine.

  In recent years, an internal combustion engine such as a gasoline engine or a diesel engine is installed, and the demand for improving fuel economy for vehicles such as automobiles that run on land has become increasingly severe. The most effective way to improve the fuel economy of a vehicle equipped with an internal combustion engine is to reduce the weight of the vehicle, but it is known that the influence of the selection of the lubricating oil composition used for the lubrication of the internal combustion engine is considerable. Yes.

  For the above reasons, companies that develop lubricating oil compositions or companies that develop lubricating oil additives to be blended in lubricating oil compositions have conventionally studied to develop lubricating oil compositions with high fuel efficiency. It is actively conducted.

  The improvement in fuel economy performance due to the lubricating oil composition is generally due to a reduction in torque of the engine rotation mainly through friction reduction by the lubricating oil composition at the sliding portion of the engine. And what has a great influence on the improvement of fuel economy performance by the lubricating oil composition is the viscosity characteristics of the lubricating oil composition and the selection of various additives, mainly the friction reducer to be blended in the lubricating oil composition. . For example, by using a low-viscosity lubricating base oil during preparation of the lubricating oil composition, the friction reducing effect exhibited by the lubricating oil composition is improved. However, when a low-viscosity lubricating base oil is used, an undesirable phenomenon that the oil consumption (the consumption of the lubricating oil composition during engine operation) increases tends to appear. There is a limit to improving fuel efficiency. On the other hand, research has been already conducted to improve the fuel economy performance of lubricating oil compositions by selecting various lubricating oil additives to be added to lubricating oil compositions in recent years. The born invention has been disclosed in a number of patent applications.

  For example, Patent Document 1 discloses a low friction characteristic having a composition in which a boron base derivative of alkenyl succinimide, an alkaline earth metal salt of salicylic acid, and molybdenum dithiophosphate and / or molybdenum dithiocarbamate are added to a lubricating base oil. Engine oil compositions are disclosed.

  Patent Document 2 discloses that a lubricating base oil contains zinc dithioalkyldithiophosphate mainly containing zinc dithioalkyldithiophosphate having a secondary alkyl group, calcium sulfonate (for example, TBN200 to 300) and calcium salicylate (for example, Disclosure that a lubricating oil composition comprising a metal-containing detergent comprising TBN 10-100) and a molybdenum dithiocarbamate having a hydrocarbon group having 8 to 23 carbon atoms exhibits excellent low wear and friction properties There is.

  Further, Patent Document 3 discloses a succinimide-based non-organic base oil having a specific kinematic viscosity and a specific total aromatic content, an alkaline earth metal salicylate, a zinc dialkyldithiophosphate, and a polybutenyl group having a molecular weight of 900 to 3,500. There is a disclosure that an engine oil composition comprising an ash dispersant, a phenolic ashless antioxidant, and molybdenum dithiocarbamate exhibits excellent fuel economy.

JP-A-5-163497 JP-A-6-336592 JP-A-8-302378

  The present invention is a lubricating oil composition comprising a molybdenum-containing friction reducing agent that is a lubricating oil additive exhibiting excellent friction reducing properties and is known to be effective in improving fuel economy. Another object of the present invention is to provide a lubricating oil composition exhibiting further excellent fuel economy.

  In order to solve the above-mentioned problems, the inventors of the present invention have studied the combined use effect of various lubricating oil additives known so far with respect to the molybdenum-containing friction reducing agent. As a result, the lubricating oil composition containing the molybdenum-containing friction reducing agent has an alkyl group having an average carbon atom number in the range of 14 to 18 and a carbon atom number in the range of 14 to 18 of 60 mol% or more. Calcium salicylate having an alkyl group and a calcium sulfonate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more And / or an overbase in combination with a calcium salicylate having an alkyl group in which the average number of carbon atoms is in the range of 20 to 28 and the number of carbon atoms in the range of 20 to 28 is 60 mol% or more The present inventors have found that a lubricating oil composition exhibiting high fuel economy can be obtained by blending a functional metal-containing detergent (composition).

  Accordingly, the present invention provides a lubricating oil composition for an internal combustion engine comprising a relatively large amount of a lubricating oil base oil and a relatively small amount of a lubricating oil additive comprising an overbased metal-containing detergent and a molybdenum-containing friction reducing agent. The overbased metal-containing detergent has an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms of 60 mol% or more (preferably 70 mol% or more of calcium salicylate having an alkyl group and an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more (preferably 70 mol% or more of calcium sulfonate having an alkyl group or an average number of carbon atoms in the range of 20 to 28 and an alkyl group in the range of 20 to 28 carbon atoms of 60 mol% or less. There (preferably 70 mol% or more) to the internal combustion engine lubricating oil composition characterized by containing a calcium salicylate having an alkyl group is.

  The lubricating base oil contained in the lubricating oil composition for internal combustion engines of the present invention is generally 70% by mass or more, preferably 80% by mass or more, based on the total amount of the lubricating oil composition.

Preferred embodiments of the lubricating oil composition of the present invention are described below.
(1) The molybdenum-containing friction reducing agent is molybdenum dithiocarbamate.

(2) Calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms of 60 mol% or more has an overbasing degree of 1 -4 calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more Alternatively, the calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 20 to 28 and an alkyl group in the range of 20 to 28 carbon atoms of 60 mol% or more has an overbasing degree of 6 to 24 Of calcium sulfonate or calcium salicylate.

(3) With respect to the degree of overbasing of calcium salicylates having an alkyl group in which the average number of carbon atoms is in the range of 14-18 and the alkyl group in the range of 14-18 is 60 mol% or more Calcium sulfonate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more, or an average number of carbon atoms of 20 to 28 And the ratio of the degree of overbasing of the calcium salicylate having an alkyl group in which the number of carbon atoms in the range of 20 to 28 is 60 mol% or more (the latter / the former) is 2 to 12 Is in range.

(4) The overbased metal-containing detergent has an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms is 60 mol% or more (preferably 70 mol) 60% by mole or more (preferably 70 moles) of an alkyl group having an alkyl group of 20% or more) and an alkyl group having an average number of carbon atoms in the range of 20 to 24 and in the range of 20 to 24 carbon atoms. % Or more) and a calcium sulfonate having an alkyl group.

(5) The overbased metal-containing detergent has an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms is 60 mol% or more (preferably 70 mol) 60% by mole or more (preferably 70 moles) of the alkyl salicylate having an alkyl group and an average number of carbon atoms in the range of 20 to 28 and in the range of 20 to 28 carbon atoms. % Or more of calcium salicylate having an alkyl group.

(6) The molybdenum-containing friction reducing agent is included in an amount in the range of 0.01 to 0.15% by mass in terms of molybdenum with respect to the total amount of the lubricating oil composition.

(7) Calcium salicylate having an alkyl group in which the average number of carbon atoms is in the range of 14 to 18 and the alkyl group in the range of 14 to 18 carbon atoms is 60 mol% or more, and the average number of carbon atoms Calcium sulfonate having an alkyl group in which the alkyl group is in the range of 20 to 24 and the number of carbon atoms in the range of 20 to 24 is 60 mol% or more, or the average number of carbon atoms is in the range of 20 to 28 In addition, the calcium salicylate having an alkyl group in which the number of carbon atoms in the range of 20 to 28 is 60 mol% or more is independently 0 in terms of calcium amount with respect to the total amount of the lubricating oil composition. It is included in an amount in the range of 0.01 to 0.4% by mass.

(8) An alkyl group having an average carbon atom number in the range of 14 to 24 and having a carbon atom number in the range of 14 to 24 has an alkyl group of 60 mol% or more (preferably 70 mol% or more). Further, a low basic calcium sulfonate having an overbasing degree of 0.1 to 2 is further included.
(9) A nitrogen-containing ashless dispersant, a zinc phosphate-based antioxidant (or zinc phosphate-based antiwear agent), and an antioxidant selected from the group consisting of a phenol-based antioxidant and an amine-based antioxidant Including.
(10) The zinc phosphate antioxidant is a mixture of zinc dihydrocarbyl dithiophosphate, and in particular, in terms of a mass ratio of zinc di (primary alkyl) dithiophosphate to zinc di (secondary alkyl) dithiophosphate. Contains a mixture of 9-9 / 1.
(11) A succinimide-based dispersant in which the nitrogen-containing ashless dispersant may be post-treated with ethylene carbonate or a boric acid compound.
(12) It further includes a molybdenum complex of succinimide which may contain sulfur.

(13) The lubricating base oil is an oil having a viscosity index of 120 to 160.
(14) A lubricating oil composition of SAW viscosity grade 0W20.

  Since the lubricating oil composition of the present invention can impart high fuel efficiency to an internal combustion engine such as a gasoline engine or a diesel engine, it can contribute to an improvement in fuel efficiency of a vehicle equipped with such an internal combustion engine. it can.

[Base oil]
As the base oil in the lubricating oil composition of the present invention, mineral oil or synthetic oil having a kinematic viscosity at 100 ° C. of ² to 50 mm ² / s is usually used. There are no particular restrictions on the type of mineral oil or synthetic oil used as the base oil, or various properties, but the sulfur content is preferably 0.1% by mass or less, and the sulfur content is 0.03% by mass or less. It is particularly preferable that it is 0.005% by mass or less.

The mineral oil base oil is preferably obtained by processing a mineral oil-based lubricating oil fraction using a combination of processing methods such as solvent refining or hydrotreating as appropriate, particularly highly hydrorefined base oil (particularly viscosity). A base oil having an index of 120 to 160, an aromatic content of 5% by mass or less, and nitrogen and sulfur contents of 50 ppm or less is preferably used.
Especially, the high viscosity index base oil (for example, viscosity index 140-160) obtained by hydroisomerizing slack wax and GTL wax is used especially suitably.

  Synthetic oils (synthetic lubricating base oils) include, for example, poly-α-olefins that are polymers of α-olefins having 3 to 12 carbon atoms, sebacic acid, azelaic acid, adipic acid represented by dioctyl sebacate, etc. Dialkyl diesters which are esters of dibasic acids and alcohols having 4 to 18 carbon atoms, polyol esters which are esters of 1-trimethylolpropane or pentaerythritol and monobasic acids having 3 to 18 carbon atoms, carbon atoms Examples thereof include alkylbenzene having an alkyl group of several 9 to 40. In general, synthetic oils are substantially free of sulfur, are excellent in oxidation stability and heat resistance, and are less likely to form residual carbon and soot once burned, so that they can be preferably used in the lubricating oil composition of the present invention.

  Mineral base oils and synthetic base oils can be used alone, but if desired, two or more mineral base oils or a combination of two or more synthetic base oils may be used. it can. Further, if desired, a mineral base oil and a synthetic base oil can be used in combination at any ratio.

[Molybdenum-containing friction reducing agent]
The lubricating oil composition of the present invention includes a molybdenum-containing friction reducing agent. Various compounds and compositions have been known so far for molybdenum-containing friction reducing agents, and specific examples of these compounds and compositions are described in Patent Documents 1 to 3, respectively.

  Preferable examples of the molybdenum-containing friction reducing agent include sulfurized oxymolybdenum dithiocarbamate, sulfurized oxymolybdenum dithiophosphate, amine-molybdenum complex compound, oxymolybdenum diethylate amide, and oxymolybdenum monoglyceride. In particular, it is particularly preferable to use a molybdenum dithiocarbamate friction reducer in the lubricating oil composition of the present invention.

  The molybdenum-containing friction reducing agent contained in the lubricating oil composition of the present invention is generally in an amount in the range of 0.01 to 0.15 mass% in terms of molybdenum amount with respect to the total amount of the lubricating oil composition.

[Overbased metal-containing detergent]
The lubricating oil composition of the present invention contains the following overbased metal-containing detergent.
Component (a): calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms of 60 mol% or more (particularly monoalkyl) (Salicylate), and (b) component: a calcium sulfonate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more. (Especially monoalkyl sulfonate) and / or calcium having an alkyl group in which the average number of carbon atoms is in the range of 20 to 28 and the alkyl group in the range of 20 to 28 carbon atoms is 60 mol% or more Salicylates (especially monoalkyl salicylates).

  In the above component (b), the former average number of carbon atoms is in the range of 20 to 24, and the alkyl group in the range of 20 to 24 carbon atoms is 60 mol% or more. Calcium sulfonate having component (b) and the latter having an average number of carbon atoms in the range of 20 to 28 and an alkyl group having a number of carbon atoms in the range of 20 to 28 of 60 mol% or more. Any of the calcium salicylates having a group can be used alone, but if necessary, they can be used in combination.

  Component (a) contained in the lubricating oil composition of the present invention, that is, an alkyl group having an average carbon atom number in the range of 14 to 18 and a carbon atom number in the range of 14 to 18 is 60 mol% or more. The calcium salicylate having an alkyl group is preferably a mixture containing 60 mol% or more (especially 70 mol% or more) of a plurality of calcium salicylates having an alkyl group having 14 to 18 carbon atoms. .

  And (b) an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more. The calcium sulfonate possessed is preferably a mixture containing 60 mol% or more (especially 70 mol% or more) of a plurality of calcium sulfonates having an alkyl group having 20 to 24 carbon atoms.

  And an alkyl group having an average number of carbon atoms in the range of 20 to 28 and an alkyl group in the range of 20 to 28 of 60 mol% or more, which is one of the components (b). The calcium salicylate possessed is preferably a mixture containing 60 mol% or more (especially 70 mol% or more) of a plurality of calcium salicylates having an alkyl group having 20 to 28 carbon atoms.

  In general, both the component (a) and the component (b) are included in the lubricating oil composition in an amount in the range of 0.01 to 0.4 mass% as a calcium amount converted value with respect to the total amount of the lubricating oil composition. It is.

  The calcium salicylate as the component (a) is preferably a calcium salicylate having an overbasing degree of 1 to 4 (particularly an overbasing degree of 1.5 to 3). Note that as the calcium salicylate, non-sulfurized or sulfurized calcium salicylate can be used.

  The calcium sulfonate and calcium salicylate as the component (b) are preferably independently calcium sulfonate and calcium salicylate having an overbasing degree of 6 to 24. This degree of overbasing is preferably in the range of 14-20 for calcium sulfonate and preferably in the range of 6-12 for calcium salicylate.

  It is preferable that said (a) component and (b) component exist in the range of 2-12 as overbasing degree ratio "(b) component / (a) component".

  In addition, the lubricating oil composition of the present invention has an average number of carbon atoms in the range of 14 to 24 and an alkyl group in the range of 14 to 24 carbon atoms of 60 mol% or more (particularly 70 mol% or more). It is preferable to further include a low basic calcium sulfonate having an alkyl group of

  In addition, salicylate-based metal-containing detergents, carboxylate-based metal-containing detergents, sulfonate-based metal-containing detergents, and / or phenate-based metal-containing detergents that are not included in the overbased metal-containing detergents described so far The overbased or low basic metal-containing detergent can be used in a relatively small amount with respect to the overbased metal-containing detergent used in the present invention.

[Other additives]
The lubricating oil composition of the present invention can further comprise other lubricating oil additives. Representative examples of such lubricating oil additives include nitrogen-containing ashless dispersants, zinc phosphate-based antioxidants (or zinc phosphate-based antiwear agents) such as zinc dihydrocarbyl dithiophosphate, and organic antioxidants ( Examples thereof, phenolic antioxidants and amine antioxidants).

  As the nitrogen-containing ashless dispersant, alkenyl or alkyl succinimide derived from polyolefin or a derivative thereof is preferably used. The addition amount is in a range of 0.01 to 0.3% by mass in terms of nitrogen content based on the total mass of the composition. Exemplary succinimides include succinic anhydrides substituted with high molecular weight alkenyl or alkyl groups and polyalkylene polyamines containing an average of 4 to 10 (preferably 5 to 7) nitrogen atoms per molecule. It can obtain by reaction of. The high molecular weight alkenyl or alkyl group is preferably a polybutene having a number average molecular weight of about 900 to 3,000.

  In the process of obtaining polybutenyl succinic anhydride by reaction of polybutene and maleic anhydride, chlorination method using chlorine is often used, but it can also be obtained by thermal reaction method without using chlorine. . It is desirable to use succinimide from polybutenyl succinic anhydride obtained by this thermal reaction method. The succinimide can be used as a so-called modified succinimide by further reacting with a boric acid compound, alcohol, aldehyde, ketone, alkylphenol, cyclic carbonate, organic acid or the like. In particular, a boron-containing alkenyl (or alkyl) succinimide obtained by reaction with a boron-containing compound such as boric acid or a boric acid compound is advantageous from the viewpoint of thermal and oxidation stability.

  In the lubricating oil composition of the present invention, an alkenyl benzylamine-based or alkenyl succinic ester-based ashless dispersant may be used in addition to or in place of the alkenyl or alkyl succinimide or derivative thereof.

  The lubricating oil composition of the present invention can contain a zinc phosphate antioxidant (or zinc phosphate wear inhibitor). The zinc phosphate-based antioxidant (or zinc phosphate-based antiwear agent) is generally selected from the group consisting of zinc dialkyldithiophosphate, zinc dialkylmonothiophosphate, and zinc dihydrocarbyl phosphate. The basic production methods and properties of these zinc phosphate wear inhibitors are well known. This zinc phosphate antiwear agent is used in the range of 0.01 to 0.12% by mass in terms of phosphorus content, but from the viewpoint of low phosphorus content and low sulfur content, 0.01 to 0.06. It is preferably used in an amount in the range of mass%.

  It is desirable that the zinc dialkyldithiophosphate has an alkylaryl group containing an alkyl group having 3 to 18 carbon atoms or an alkyl group having 3 to 18 carbon atoms. Particularly preferred is an alkyl group derived from a secondary alcohol having 3 to 18 carbon atoms, or a primary alcohol having 3 to 18 carbon atoms and 3 to 18 carbon atoms, which is particularly effective for suppressing wear. Dialkyldithiophosphate zinc containing an alkyl group derived from a mixture of a secondary alcohol. Zinc dialkyldithiophosphates from primary alcohols tend to be excellent in heat resistance. These zinc dialkyldithiophosphates may be used alone, but are preferably used in a mixture mainly composed of secondary alkyl group type and / or primary alkyl group type.

The lubricating oil composition of the present invention preferably contains an organic antioxidant. As the organic antioxidant, it is preferable to use an antioxidant phenol compound and / or an antioxidant amine compound in an amount in the range of 0.01 to 5% by mass (preferably 0.1 to 3% by mass). . Of these, diarylamine-based antioxidants and / or hindered phenol-based antioxidants are preferred. These antioxidants are also effective in improving high temperature cleanability. In particular, diarylamine-based antioxidants are advantageous in this respect because they have a base number derived from nitrogen. On the other hand, hindered phenolic antioxidant is advantageous in prevention of the NO _x oxidation deterioration.

  Examples of hindered phenol antioxidants include 2,6-di-t-butyl-p-cresol, 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-methylenebis. (6-t-butyl-o-cresol), 4,4′-isopropylidenebis (2,6-di-t-butylphenol), 4,4′-bis (2,6-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 2,2-thio-diethylenebis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], and octyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3- (3,5-di-t- Butyl-4- It may be mentioned hindered phenols such as hydroxyphenyl) octadecyl propionate.

  Examples of diarylamine antioxidants include mixed alkyl diphenylamines having 4 to 9 carbon atoms, p, p′-dioctyldiphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, alkylated α-naphthylamine, And diarylamines, such as alkylation-phenyl-alpha-naphthylamine, can be mentioned. The hindered phenol-based antioxidant and the diarylamine-based antioxidant can be used alone or in combination as desired. Moreover, you may use together oil-soluble antioxidant other than these.

  The lubricating oil composition of the present invention may contain a succinimide oxymolybdenum complex, particularly a succinimide sulfur-containing oxymolybdenum complex, in order to further improve the antioxidant properties. The sulfur-containing oxymolybdenum complex of succinimide exhibits a further improvement in antioxidant properties, particularly when used in combination with the above-mentioned phenol-based or amine-based antioxidant.

The lubricating oil composition of the present invention can further contain 5% by mass or less, particularly 0.01 to 5% by mass of alkali metal borate hydrate. Many of these compounds contain ash or sulfur and the like, but can be used by adjusting the addition amount in consideration of the properties of the entire lubricating oil composition of the present invention. Examples of the alkali metal borate hydrate include compounds typified by compounds synthesized by the methods described in US Pat. Nos. 3,929,650 and 4,089,790. For example, alkali metal or alkaline earth metal neutral sulfonate is carbonated in the presence of an alkali metal hydroxide to obtain an overbased sulfonate, and boric acid is reacted with this to disperse fine particles of alkali metal borate obtained (A desirable ashless dispersant such as succinimide is allowed to coexist during the carbonation reaction). Here, potassium or sodium is desirable as the alkali metal. Specific examples thereof include a fine particle dispersion having a particle size of about 0.3 μm or less represented by a composition formula: KB ₃ O ₅ .H ₂ O dispersed in neutral calcium sulfonate and succinimide.

  The lubricating oil composition of the present invention desirably further contains a viscosity index improver in an amount of 20% by mass or less (preferably in the range of 1 to 20% by mass). Examples of the viscosity index improver include polymer compounds such as polyalkyl methacrylate, ethylene-propylene copolymer, styrene-butadiene copolymer, and polyisoprene. Alternatively, a dispersion-type viscosity index improver or a multifunctional viscosity index improver that imparts dispersion performance to these polymer compounds can be used. These viscosity index improvers can be used alone, but any viscosity index improver may be used in combination of two or more.

  The lubricating oil composition of the present invention may further contain various auxiliary additives. Examples of such auxiliary additives include, as antioxidants or antiwear agents, zinc dithiocarbamate, methylenebis (dibutyldithiocarbamate), oil-soluble copper compounds, sulfur compounds (eg, sulfurized olefins, sulfurized esters, Polysulfide), phosphate ester, phosphite ester, thiophosphate ester, organic amide compound (eg, oleylamide), and the like. In addition, compounds such as benzotriazole compounds and thiadiazole compounds that function as metal deactivators can be added. In addition, polyoxyalkylene nonionic surfactants such as polyoxyethylene alkylphenyl ethers functioning as rust inhibitors or demulsifiers and copolymers of ethylene oxide and propylene oxide can also be added. Various amines, amides, amine salts, and derivatives thereof that function as friction modifiers, fatty acid esters of polyhydric alcohols, or derivatives thereof can also be added. Furthermore, various compounds that function as an antifoaming agent or a pour point depressant can also be added. These auxiliary additives are preferably used in an amount of 3% by mass or less (particularly in the range of 0.001 to 3% by mass) with respect to the lubricating oil composition.

[Example 1] to [Example 3], [Comparative Example 1] to [Comparative Example 3]
(1) Production of Lubricating Oil Composition Lubricating oil composition according to the present invention is prepared by adding the following additive components to the base oil as a lubricating oil composition (test oil) for performance evaluation, and according to the formulation shown in Table 1. ([Example 1] to [Example 3]) and a comparative lubricating oil composition ([Comparative Example 1] to [Comparative Example 3]) were produced. The lubricating oil composition was a SAE viscosity grade of 0W20 by addition of a viscosity index improver, and was adjusted so that the kinematic viscosity at 100 ° C. was 7.7 to 7.8 mm ² / s.

(2) Base oil and additives 1) Base oil Mineral oil base oil produced through slack wax as a raw material through hydrogenation, fractional distillation, and dewaxing processes (kinematic viscosity at 100 ° C: 4.1 mm ² / s Viscosity index: 137)
2) Additive

[Nitrogen-containing ashless dispersant]
Succinimide-based dispersant obtained by post-treatment of bis-type succinimide derived from polybutene having a number average molecular weight of about 2300 with ethylene carbonate (N content: 1.0% by mass)

[Metal-containing detergent]
a) Overbased Ca-salicylate (1) [Ca-sali-1]: having an alkyl group having 14 to 18 carbon atoms (provided that an alkyl group having 14 to 18 carbon atoms is an entire alkyl group) Calcium monoalkyl salicylate (Ca: 6.1% by mass, S: 0.1% by mass, TBN: 170 mg KOH / g, degree of overbasing: 2.3)
b) Overbased Ca-sulfonate [Ca-sulf-1]: having an alkyl group having 20 to 24 carbon atoms (provided that an alkyl group having 20 to 24 carbon atoms is about 80 of the entire alkyl group) Calcium alkyltoluenesulfonate (Ca: 16.0% by mass, S: 1.6% by mass, TBN: 423 mg KOH / g, degree of overbasing: 17)
c) Overbased Ca-salicylate (2) [Ca-sali-2]: having an alkyl group having 20 to 28 carbon atoms (provided that an alkyl group having 20 to 28 carbon atoms is the entire alkyl group) Calcium monoalkyl salicylate (Ca: 11.4 mass%, S: 0.2 mass%, TBN: 320 mg KOH / g, degree of overbasing: 8.2)
d) Low basic Ca-sulfonate [Ca-sulf-2]: having an alkyl group having 14 to 24 carbon atoms (provided that an alkyl group having 14 to 24 carbon atoms is about 80 of the entire alkyl group) Calcium alkylbenzenesulfonate (Ca: 2.4% by mass, S: 2.9% by mass, TBN: 17 mg KOH / g, degree of overbasing: 0.34)

[Molybdenum-containing friction reducing agent]
Sulfurized oxymolybdenum dithiocarbamate (Mo-DTC, Mo: 10% by mass, S: 11% by mass)

[Zinc phosphate antioxidant]
Di (secondary alkyl) dithiophosphate zinc (ZnDTP-1, P: 7.2 mass%, Zn: 7.8 mass%, S: 14 mass%)
Zinc di (primary alkyl) dithiophosphate (ZnDTP-2, P: 7.3 mass%, Zn: 8.4 mass%, S: 14 mass%)
[Antioxidant]
Amine-based antioxidant: Dialkyldiphenylamine [Molybdenum complex containing succinimide sulfur]
Oxymolybdenum-succinimide complex compound containing sulfur (Mo containing complex, Mo: 5.5% by mass, S: 0.2% by mass, N: 1.6% by mass, TBN: 10 mg KOH / g)
[Viscosity index improver]
Polymethacrylate viscosity index improver

(3) Evaluation of lubricating oil composition a) Test method Using an inline 4-cylinder gasoline engine with a displacement of 1.8L (valve mechanism is a roller type), the crankshaft is driven by an electric motor via a torque meter and rotated Torque was measured. However, in order to minimize the effect of piston pumping loss, the spark plug was removed and the test was conducted in an open atmosphere. The oil temperature was maintained at 100 ° C., a test for 150 seconds was performed at each rotation number, and an average torque value was calculated from the torque measured for 120 seconds after 30 seconds had elapsed from the start of the test.
Further, a reference oil (SAE viscosity grade: 0 W20, kinematic viscosity at 100 ° C .: 8.9 mm ² / s) prepared without adding a molybdenum-containing friction reducing agent was prepared, and the torque value of the reference oil and the above average The torque reduction rate (%) of each test oil was determined from the torque value and listed in Table 1.

b) Test results Table 1 shows the test results of the above test methods.

Table 1
────────────────────────────────────
Test Oil Composition Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3
────────────────────────────────────
Nitrogen-containing ashless dispersant 0.03 0.03 0.03 0.03 0.03 0.03
Ca-Sari-1 0.12 0.06 0.12 0.18--
Ca-Sul-1 0.06 0.12--0.18-
Ca-Sari-2--0.06--0.18
Ca-Sul-2 0.02 0.02 0.02 0.02 0.02 0.02
Mo-DTC 0.07 0.07 0.07 0.07 0.07 0.07
ZnDTP-1 0.03 0.03 0.03 0.03 0.03 0.03
ZnDTP-2 0.05 0.05 0.05 0.05 0.05 0.05
Antioxidant 1.2 1.2 1.2 1.2 1.2 1.2
Mo-containing complex 0.4 0.4 0.4 0.4 0.4 0.4
────────────────────────────────────
[Test results]
Torque reduction rate (%)
550 rpm 6.2 5.9 6.0 5.5 5.3 5.7
950 rpm 4.1 4.2 3.9 3.5 3.7 3.6
1500rpm 2.0 2.2 2.0 1.6 1.9 1.3
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  Note: The addition amount of the additives shown in Table 1 is the addition amount (unit: mass%) of the antioxidant and the Mo-containing complex itself, and includes a nitrogen-containing ashless dispersant, a Ca-containing detergent ( For Ca-sari-1, Ca-sul-1, Ca-sari-2, Ca-sul-2), MoDTC, and zinc-containing compounds (ZnDTP-1, ZnDTP-2), N amount, Ca amount, It is the conversion value (unit: mass%) of Mo amount, Zn amount, and P amount.

  As is clear from the above evaluation test results, the lubricating oil compositions (Examples 1 to 3) according to the present invention are different from the lubricating oil compositions (Comparative Examples 1 to 3) having different overbased metal-containing detergent compositions. Compared with it, the torque reduction rate is clearly higher.

Claims (15)

  A lubricating oil composition for an internal combustion engine comprising a relatively small amount of a lubricating base oil and a relatively small amount of a lubricating oil additive comprising an overbased metal-containing detergent and a molybdenum-containing friction reducing agent, A calcium salicylate having an alkyl group in which a basic metal-containing detergent has an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms is 60 mol% or more; Calcium sulfonate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more, or an average number of carbon atoms of 20 to 28 And a calcium salicylate having an alkyl group in which the number of carbon atoms in the range of 20 to 28 is 60 mol% or more. Seki lubricating oil composition.   The lubricating oil composition for an internal combustion engine according to claim 1, wherein the molybdenum-containing friction reducing agent is molybdenum dithiocarbamate.   A calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms of 60 mol% or more has an overbasing degree of 1 to 4 Calcium sulfonate having a carbon salicylate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group having a number of carbon atoms in the range of 20 to 24 of 60 mol% or more, or an average carbon Calcium sulphonate having an alkyl group in which the number of atoms in the range of 20 to 28 and the number of carbon atoms in the range of 20 to 28 is 60 mol% or more is a calcium sulfonate having an overbasing degree of 6 to 24 Or the lubricating oil composition for internal combustion engines of Claim 1 which is calcium salicylate.   Average carbon relative to the degree of overbasing of calcium salicylates having an alkyl group having an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms of 60 mol% or more Calcium sulfonate having an alkyl group having an atom number in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more, or an average carbon atom number in the range of 20 to 28 The ratio of the degree of overbasing of the calcium salicylate having an alkyl group in which the number of carbon atoms in the range of 20 to 28 is 60 mol% or more is in the range of 2 to 12. The lubricating oil composition for internal combustion engines as described.   Calcium salicylate having an overbased metal-containing detergent having an alkyl group in which the average number of carbon atoms is in the range of 14 to 18 and the alkyl group in the range of 14 to 18 carbon atoms is 60 mol% or more And a calcium sulfonate having an alkyl group having an average number of carbon atoms in the range of 20 to 24 and an alkyl group in the range of 20 to 24 carbon atoms of 60 mol% or more. A lubricating oil composition for internal combustion engines.   Calcium salicylate having an overbased metal-containing detergent having an alkyl group in which the average number of carbon atoms is in the range of 14 to 18 and the alkyl group in the range of 14 to 18 carbon atoms is 60 mol% or more And calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 20 to 28 and an alkyl group in the range of 20 to 28 carbon atoms of 60 mol% or more. A lubricating oil composition for internal combustion engines.   The lubricating oil composition for an internal combustion engine according to claim 1, wherein the molybdenum-containing friction reducing agent is contained in an amount in the range of 0.01 to 0.15 mass% in terms of molybdenum based on the total amount of the lubricating oil composition. .   Calcium salicylate having an alkyl group having an average number of carbon atoms in the range of 14 to 18 and an alkyl group in the range of 14 to 18 carbon atoms of 60 mol% or more and an average number of carbon atoms of 20 to 24 And a calcium sulfonate having an alkyl group in which an alkyl group having a carbon atom number in the range of 20 to 24 is 60 mol% or more or an average carbon atom number in the range of 20 to 28, and carbon Calcium salicylate having an alkyl group having an alkyl group in the range of 20 to 28 atoms and having an alkyl group of 60 mol% or more is independently 0.01 to 0.3 in terms of calcium amount, relative to the total amount of the lubricating oil composition. The lubricating oil composition for an internal combustion engine according to claim 1, which is contained in an amount in the range of 0.4 mass%.   The average number of carbon atoms is in the range of 14 to 24, and the alkyl group in the range of 14 to 24 carbon atoms has an alkyl group of 60 mol% or more, and the degree of overbasing is 0.1 to 2 The lubricating oil composition for internal combustion engines according to claim 1, further comprising a low basic calcium sulfonate.   The lubricant according to claim 1, further comprising a lubricating oil additive selected from the group consisting of a nitrogen-containing ashless dispersant, a zinc phosphate-based antioxidant or anti-wear agent, and a phenol-based antioxidant and an amine-based antioxidant. Lubricating oil composition for internal combustion engines.   A zinc phosphate-based antioxidant or antiwear agent is a mixture having a ratio of 1/9 to 9/1 in terms of mass ratio of zinc di (primary alkyl) dithiophosphate and zinc di (secondary alkyl) dithiophosphate. The lubricating oil composition for an internal combustion engine according to claim 10, which is contained.   The lubricating oil composition for an internal combustion engine according to claim 10, wherein the nitrogen-containing ashless dispersant is a succinimide-based dispersant which may be post-treated with ethylene carbonate or a boric acid compound.   The lubricating oil composition for an internal combustion engine according to claim 1, further comprising a molybdenum complex of succinimide which may contain sulfur.   The lubricating oil composition for an internal combustion engine according to claim 1, wherein the lubricating base oil is an oil having a viscosity index of 120 to 160.   The lubricating oil composition for an internal combustion engine according to claim 1, which is a lubricating oil composition of SAW viscosity grade and 0W20.